High daytime temperature induces male sterility with developmental defects in male reproductive organs of Arabidopsis

High-temperature (HT) stress is an environmental factor that limits growth and productivity in various ways, depending upon organ type and the temperature and duration at which plants are challenged by HT-induced challenges. Thus, understanding how plants respond to heat is crucial if researchers are to develop crops that can withstand a rise in average temperatures due to climate change. In particular, the impacts of HT on reproductive organs are directly linked to crop productivity and/or food security, two key issues in agriculture. We used the Arabidopsis thaliana model system to examine how an elevated daytime temperature might influence the development of sexual organs. After 2 days of exposure to 35/22 °C (day/night), fertility gradually decreased for 3-week-old plants. After 5 days of exposure, fertility was dramatically reduced and plants displayed abnormal stamens, i.e., short filaments, poor production of viable pollen grains, and defective anther dehiscence. In contrast, female organs remained functional. Furthermore, the developing pollen grains from stressed plants underwent aberrant cytokinesis that generated a high proportion of unreduced, aneuploid, and diploid pollen. The formation of enlarged grains may have been due to polyploidization, which contributed to temperature-induced speciation and evolution. Our findings will aid in the molecular genetic dissection of HT-related damage in male reproductive organs, which are the most vulnerable to such stress.